Lubricators have been used in the past for pumping predetermined quantities of mineral or synthetic oil or lubricant to machinery injection points. These lubricators deliver this predetermined quantity of lubricant normally under pressure and at regular intervals.
The lubricator generally comprises a reservoir, pumps and drive mechanism that can be either electric motor drive or shaft driven from the machinery to be lubricated. These lubricators have been used with rubber machinery, food process machinery, reciprocating air compressors, reciprocating gas compressors, reciprocating pumps, engines and other similar machinery.
The lubricator pumps are actuated by a central cam shaft attached to the drive mechanism to move the respective pump pistons. However, in the past the cylinder surrounding the pump piston has been integral with the pump housing, such as shown in the prior art device of FIG. 4 manufactured by the assignee of the present invention. Assignee's device in FIG. 4 is rated for a 1/4 inch piston for pumping up to 6000 psi (0.018 inch.sup.3 per stroke max).
An example of another lubricator pump is the "Manzel" model 88 pump manufactured by Lubriquip, Inc. of Cleveland, Ohio. This model 88 pump also includes an integrated cylinder with the pump housing. In particular, the model 88 pump housing is fabricated from aluminum and includes an integrated cast iron sleeve to receive the movable piston. Other examples of lubricator pumps are the model 55 and 55i pumps manufactured by Lincoln Centralized Lubrication Systems, a Pentair Company, of St. Louis, Mo. The model 55 and 55i pumps feature a one-piece pump body with an integral cylinder. Both the model 88 pump and the assignee's device shown in FIG. 4 include an indicator port for communicating the piston chamber with the vacuum chamber in the sight glass assembly or sight well. This indicator port communicates lubricant slippage between the inner surface of the cylinder and the piston to the sight glass assembly. Above normal volume of lubricant in the sight glass assembly or variance in the volume in the sight glass assembly during operation of the pump indicates lubricant slippage in the cylinder piston assembly. The operator could then perform needed maintenance or, if needed, replacement of the entire pump housing if the cylinder piston assembly is found to be defective.
The model 88 pump and the model 55 and 55i pumps are available in a variety of piston sizes, e.g. 1/4" and 3/8" to provide varied lubricant output. Because of the pump integrated cylinder, when a different size pump piston is desired by the operator, a new pump would be required.
It would be desirable to have a replaceable cylinder piston assembly for a pump housing of a lubricator. This replaceability of the cylinder piston assembly would allow interchangeability of different sizes of pump pistons to provide desired lubricant output. Additionally, a lubricator pump housing having a replaceable cylinder piston assembly would save on inventory costs, as a similar cylinder piston assembly could be replaced on a lubricator pump housing, eliminating the need, for these replacements, to stock complete pump housings or pumps. Additionally, a replaceable or removable cylinder piston assembly could reduce manufacturing costs since one of the critical areas of manufacture is the cylinder piston assembly. If a defective cylinder piston assembly were manufactured, only that assembly would need to be discarded, not the complete pump housing. Also, repair could be facilitated since a number of replacement cylinder piston assemblies with different piston sizes could be transported to field repair lubricators.